This invention relates to a non-impact printing apparatus. More specifically, this invention relates to a thermal ink jet printing apparatus.
There have been proposed various printing systems ranging from impact types to non-impact types. Non-impact type printers, which provide less noise than the impact type printers, include electrophotographic, electrostatic, thermal and ink jet printers.
As an example of a non-impact printing apparatus, there is known a thermal ink jet printer which produces an image by using a thermal head and an ink carrier film having a plurality of holes or recesses. In a conventional apparatus of this type such as disclosed in Japanese Patent Disclosure No. 60-71260, an ink carrier film is disposed between a thermal head and a printing paper and is quickly heated to generate bubbles in the ink held in holes by the thermal head. The thermal head has a plurality of heating elements. In operation, a driving circuit provides a set of driving pulses according to the image to be printed and thus the selected heating elements are energized so that when the ink-filled holes reach the surface of the selected heating elements, the selected heating elements heat the holes to generate bubbles in them, whereby the air pressure of the generated bubbles causes ejection of the ink toward the printing paper.
In the printing apparatus mentioned above, however, as the ink in the holes is ejected toward the printing paper by the pressure of air bubbles generated in the ink, it is too difficult to precisely control the ejection of ink drops. As a result, the apparatus may not achieve high-quality recording. It is, therefore, considered to achieve high-quality recording by arranging the holes in an appropriate manner.